Ingress controllers (for example ingress-nginx) and testing with curl and Host headers

An Ingress object does nothing on its own. An Ingress controller is the component that watches Ingress resources through the API and configures a reverse proxy to route traffic accordingly. Kubernetes does not ship a controller in its core; the cluster needs one installed. If none is running, Ingresses are accepted but no traffic is routed, and the ADDRESS column of kubectl get ingress stays empty.